A portion of the total airflow from the compressor may be extracted to cool various turbine components. The extracted air airflow, however, may not be used in the combustion process to produce useful work. Similarly, an ejector may use compressor bleed air extracted from different compressor stages at different pressures and temperatures to provide an immediate pressure and temperature airflow to the turbine. Depending upon local ambient conditions and other types of operational parameters, the ejector may be used or bypassed. The adequate management and control of these parasitic extraction flows therefore may increase the overall performance and efficiency of the gas turbine engine.
In addition to compressor flows, certain exhaust frame cooling systems use an external blower to provide cooling air to an exhaust frame manifold. Such a blower generally provides a cooling flow at a substantially constant rate. Although an external blower may be less “expensive” than compressor extraction flows, the use of the blower still has an impact on overall performance and efficiency.
Both the compressor extraction flows and the ejector use various types of valves to regulate the cooling flows. These valves, however, are generally positioned in high temperature locations about the compressor and the turbine. Such high temperature locations may cause loss of actuator seals, loss of actuator spring paint, and other types of damage. Valve damage and/or failure can have an impact on overall gas turbine performance and efficiency.